hey @max, welcome to the Tulip Community, it would be great if you could introduce yourself at: Welcome to the Community, let's meet!!
just to confirm, did you take a look at all of these sensors: Photoelectric Sensors | Frontline Operations Platform?? but so long as the sensors output between 12V and 24V, you should be able to connect them to an I/O Gateway. if you can share which sensors you can find in the UK, we can confirm whether or not they will work!!
but aside from the sensor and the Gateway, there’s nothing else that’s needed. you’ll be able to use the ‘Device > Pin Changed’ Trigger in your apps:
hope this helps, let us know if you have further questions!!